<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button>按钮</button>
    <div>
    </div>
    <script>
        var div = document.querySelector('div');
        var time = 5;
        div.innerHTML = time + '秒后跳转到新页面';s
        setInterval(function() {
            if (time == 0) {
                location.href = 'http://www.itcast.cn';
            } else {
                div.innerHTML = time + '秒后跳转到新页面';
                time--;
            }
        }, 1000)
    </script>
    <!-- <script>
        var div = document.querySelector('div');
        var timer = 5;
        setInterval(function() {
            if (timer == 0) {
                location.href = 'http://www.itcast.cn';
            } else {
                div.innerHTML = '您将在' + timer + '秒钟之后跳转到首页';
                timer--;
            }

        }, 1000);
    </script> -->
</body>

</html>